This would be as easy as checking the directories in the steamapps directory. However I am sure lgdb staff does not have the resources to develop this. If you are interested though I'd love to help you plan and test this software.

It is not harsh, this is just how “open source” is defined.
Read the definition of “open source”: https://opensource.org/osd
CC-Whatever-NC is in clear violation of condition 1 “Free Distribution”, sorry.